1. Field of the Invention
The present invention relates to a line connection switching apparatus and, more particularly, to a line connection switching apparatus for switching a line used both for speech communication and data communication performed by data communication supply.
2. Description of the Related Art
Recently, a single communication line is used both for speech communication performed by a speech communication apparatus such as a telephone set and data communication performed by a data communication apparatus such as a facsimile apparatus. When a communication line is used in this manner, a special communication line for data communication using a facsimile apparatus or the like need not be provided in addition to a telephone line for speech communication. Therefore, such a system is very advantageous in terms of cost.
In this system, a line connection switching apparatus is used to selectively connect one of the speech and data communication apparatus to the communication line so that the communication line can be switched to either speech communication or data communication, i.e., can be commonly used. However, in general, the communication line is mainly used for speech communication in a conventional system. Therefore, a line connection switching apparatus of this type responds to an incoming call first as a telephone set. Then, if speech from a caller is input in correspondence to this response, the line connection switching apparatus causes the communication line to perform speech communication while the communication line is connected to a speech communication terminal such as a telephone set. Meanwhile, if no speech is input from a caller, the line connection switching apparatus monitors the input for a predetermined time interval, confirms that no speech is input throughout the predetermined time interval, and then switches the communication line to a data communication terminal such as a facsimile apparatus. Thereafter, data communication (facsimile reception) is performed. This is described in Japanese Patent Disclosure (Kokai) No. 58-87956.
When the communication line is mainly used for data communication, a predetermined facsimile transmission sequence is performed when, e.g., an incoming call is detected. Then, after a failure of the facsimile transmission sequence is confirmed by, e.g., visual observation, an operation for switching the communication line to the speech communication apparatus is activated.
However, in order to switch the communication line from the speech communication apparatus to the data communication apparatus or vice versa in this manner, monitoring for the predetermined time interval must be performed. For this reason, connection switching of the line cannot be rapidly performed when an incoming call is input. Assuming that inputting of a speech signal requires a predetermined period of time, a time is required for a callee to detect this and perform connection switching to the data communication apparatus. It is proposed to control connection switching by sending a predetermined control signal from a caller. For example, a predetermined command from a callee is supplied to and confirmed by a caller. In this case, however, a control system is bulky and troublesome.
As described above, according to the conventional line connection switching apparatus, connection switching of the speech communication apparatus and the data communication apparatus to the communication line cannot be rapidly and easily performed for a predetermined time interval immediately after the communication line is connected.